Insulating an attic or make more holes?

[Bennylava]

Hi all. I'm a newb to hvac and cooling problems. I live in Texas and my AC system is running non stop. So I paid the obligatory $500 for the reputable AC service company to come check it out. They spent about 3 hours but told me the system appears fine. And that it's likely the load that's keeping it running. So air is escaping my house.

Or maybe it's the attic. I'm pretty sure if you stayed up there for an hour in the summer, you'd die. Could the high heat in the attic be making the AC run non-stop? And if so, what's the most cost effective way to fix the problem? Should I pay to have that foam sprayed up there? Or should I have them use regular old, roll out insulation?

And what about adding better ventilation? I used to know a cop who had some weird vent system put in, and there were two fans on each end that vented attic air to the outside. A solar panel on each end, ran the electric motor. He said it resulted in his house staying very cool and his AC hardly ran anymore. Anyone know what that system would be? Any insight would be greatly appreciated, thank you.

 

[65ranchero]

I'll start
How old is the house?

What kind of roof?
does it already have soffit vents?
Is there a ridge vent?
Is there insulation in the attic floor and what kind?

 

[dcg9381]

Traditionally insulated homes in TX are not "heated space HVAC" - which means they are not cooled space either. It's just brilliant. Take the most critical piece of home infrastructure and stuff it in an attic where it may reach 120-140 and expect it to cool the house down.

Texas is hitting all time record highs right now.

You can retrofit radient barriers into traditional homes. IMHO, it does make a difference on the attic temps.

I don't know if your attic is "vented enough" or not, but when it's 103 with a heat index of 115, not sure how to tell.

Maybe show us pictures of your attic design. Most have vented soffits and a ridge line vent. If you have that, you can add additional vents to the roof that are powered by solar to "pull" cool air from the soffits.

But in order to pull or push air, it has to go somewhere. You can't just have two attic fans that push or pull from the outside.

I think the best option is to fully seal an attic with foam insulation - which means no roof vents or soffit vents. The decrease in attic temps is amazing. I've seen homes that have been retrofitted in this way.

 

[racecougar]

In addition to the questions posted above, is the AC condenser in the attic, or is it outside?

 

[462867aa]

I have power vents on my roof. Seems to make a good difference. I replaced the flex duct with hard pipe. That made a WORLD of difference.

 

[Bennylava]

To answer the questions - The house was built in 1983. It has a shingle roof. I believe they call the shingles "Architectural". The AC unit is outside the house, not in the attic.

I'm not sure what soffit vents are, but it does have vents around the edge of the roof. There are only small ridges above a couple of windows. There's no big roof ridges where you might see that big triangular vent on some houses.

There doesn't appear to be much insulation on the attic floor. Looks like some attempt was made in the old days, but it's not the spray foam stuff. It looks like loose jute backing from an automobile. But darker in color, and there's not all that much of it. I also saw that one of the turbine vents isn't spinning, while the other one is.

I do have attic foil, and it did make a difference in the electric bill. It lowered our bill by about $75 per month in the summer time. But it just ain't enough, the AC still can't keep up with the load apparently.

 

[racecougar]

Are you able to take some photos of the venting and insulation that you have in place currently? Soffit vents are typically perforated soffit panels, but they can also be screened holes, actual vents installed into the soffit, etc. If you have turbines on the roof, I would doubt that there is a ridge vent, but I would expect to see soffit vents.

Is the insulation blown cellulose? Are you able to measure its depth?

If adding a reflective barrier dropped the monthly electric bill $75, I'd hate to see just how high that bill is!

 

[dcg9381]

There doesn't appear to be much insulation on the attic floor. Looks like some attempt was made in the old days, but it's not the spray foam stuff. It looks like loose jute backing from an automobile. But darker in color, and there's not all that much of it. I also saw that one of the turbine vents isn't spinning, while the other one is.

I do have attic foil, and it did make a difference in the electric bill. It lowered our bill by about $75 per month in the summer time. But it just ain't enough, the AC still can't keep up with the load apparently.

Look at the recommendations for R value in homes by climate zone. Sounds like you're woefully uninsulated in the attic, which is relatively easy and inexpensive to fix (compared to other things).

The other thing to tell is is the difference in temperature between your HVAC intake and vent temperature.

 

[starquestMM]

If the attic insulation is insufficient, you'll be able to notice the ceiling is warm/hot to the touch. There will be a layer of hot air along the ceiling that grows as the temps go up.

 

[fitter30]

Call your electric company see if they offer a energy audit that includes a blower door test. That test tells how tight the house is. They might offer pics with FLIR camera shows how well the insulation is.

 

[FredWanaker]

When it is 105+ outside for many days in a row, heat is going to soak thru many inches of insulation regardless what is done. Nothing is going to be a quick solution. A good insulation company can tell you if you have enough in the attic, and what the air vents are up there. When it is 105F+ here in NorCal, it can still be 90F at midnight. A HVAC system is going to run a good period of time, shut off, then run again for long while. You do not want an HVAC to pop on, cool the house down in 10 minutes then shut off. That is very inefficient. If the HVAC system is original to 1983, it will be inefficient by its design. Ducting in the attic can have many openings in it, dumping lots of wasted AC into the attic. The system in this house from 1979 had an efficiency of SEER 6 with a poorly built duct system that leaked terribly. The replacement, now from 2004-2005 or so has a SEER of 14 and no leaks whatsoever in the ducting that replaced the old. The attic has many more vents, is R50 instead of the original R19, which was standard at that time, and is much cooler in the space. Even so the AC unit, which is properly sized for the house, runs a good length of time in this weather. It is 111F here today. Modern HVAC units today are usually between SEER 13 and SEER 21, and you get what you pay for. How does your insulation work on cold winter days?

One thing you can do now is super cool the house in the early morning hours. That helps.

also this is a very good suggestion but it may take you months to get one in this weather:

Call your electric company see if they offer a energy audit that includes a blower door test. That test tells how tight the house is. They might offer pics with FLIR camera shows how well the insulation is.